diff --git a/artifacts/scripting/headers/sfall.h b/artifacts/scripting/headers/sfall.h
index 09af7215..44510f71 100644
--- a/artifacts/scripting/headers/sfall.h
+++ b/artifacts/scripting/headers/sfall.h
@@ -51,6 +51,7 @@
 #define HOOK_WITHINPERCEPTION (23)
 #define HOOK_INVENTORYMOVE    (24)
 #define HOOK_INVENWIELD       (25)
+#define HOOK_ADJUSTFID        (26)
 #define HOOK_GAMEMODECHANGE   (31)
 
 //Valid arguments to list_begin
diff --git a/artifacts/scripting/hookscripts.txt b/artifacts/scripting/hookscripts.txt
index 135da603..871dda65 100644
--- a/artifacts/scripting/hookscripts.txt
+++ b/artifacts/scripting/hookscripts.txt
@@ -465,6 +465,20 @@ int     ret0 - overrides hard-coded handler (-1 - use engine handler, any other
 
 -------------------------------------------
 
+HOOK_ADJUSTFID (hs_adjustfid.int)
+
+Runs after calculating character figure FID on the inventory screen, whenever the game decides that character appearance might change.
+Also happens on other screens, like barter.
+
+NOTE: FID has following format: 0x0ABBCDDD, where A is object type, BB - animation code (always 0 in this case), C - weapon code, DDD - FRM index in LST file.
+
+int     arg0 - the vanilla FID calculated by the engine according to critter base FID and armor/weapon being used
+int     arg1 - the modified FID calculated by the internal sfall code (like Hero Appearance Mod)
+
+int     ret0 - overrides the calculated FID with provided value
+
+-------------------------------------------
+
 HOOK_GAMEMODECHANGE (hs_gamemodechange.int)
 
 Runs once every time when the game mode was changed, like opening/closing the inventory, character screen, pipboy, etc.
diff --git a/sfall/FalloutFuncOffs_def.h b/sfall/FalloutFuncOffs_def.h
index f12cb2cf..ea21b548 100644
--- a/sfall/FalloutFuncOffs_def.h
+++ b/sfall/FalloutFuncOffs_def.h
@@ -552,6 +552,7 @@ FUNC(win_register_button_disable_,    0x4D8674)
 FUNC(win_register_button_sound_func_, 0x4D87F8)
 FUNC(win_show_,                       0x4D6DAC)
 FUNC(win_width_,                      0x4D7918)
+FUNC(windowCheckRegion_,              0x4B6858)
 FUNC(windowDisplayBuf_,               0x4B8EF0)
 FUNC(windowDisplayTransBuf_,          0x4B8F64)
 FUNC(windowGetBuffer_,                0x4B82DC)
diff --git a/sfall/FalloutFuncs_def.h b/sfall/FalloutFuncs_def.h
index 202afca4..0f7684a8 100644
--- a/sfall/FalloutFuncs_def.h
+++ b/sfall/FalloutFuncs_def.h
@@ -118,6 +118,7 @@ WRAP_WATCOM_FUNC2(long, interpretFindProcedure, TProgram*, scriptPtr, const char
 WRAP_WATCOM_FUNC1(DWORD, interpretPopShort, TProgram*, scriptPtr) // Pops value type from Data stack (must be followed by InterpretPopLong)
 WRAP_WATCOM_FUNC1(DWORD, interpretPopLong, TProgram*, scriptPtr)  // Pops value from Data stack (must be preceded by InterpretPopShort)
 WRAP_WATCOM_FUNC2(long, intface_get_attack, DWORD*, hitMode, DWORD*, isSecondary)
+WRAP_WATCOM_FUNC0(long, intface_is_item_right_hand)
 WRAP_WATCOM_FUNC0(long, intface_is_hidden)
 WRAP_WATCOM_FUNC0(void, intface_redraw) // Redraws the main game interface windows (useful after changing some data like active hand, etc.)
 WRAP_WATCOM_FUNC0(void, intface_toggle_item_state)
diff --git a/sfall/HeroAppearance.cpp b/sfall/HeroAppearance.cpp
index d7441e1d..107589e7 100644
--- a/sfall/HeroAppearance.cpp
+++ b/sfall/HeroAppearance.cpp
@@ -20,6 +20,7 @@
 
 #include "main.h"
 #include "FalloutEngine.h"
+#include "Inventory.h"
 #include "LoadGameHook.h"
 #include "LoadOrder.h"
 #include "Message.h"
@@ -266,21 +267,12 @@ static void __declspec(naked) AdjustHeroBaseArt() {
 }
 
 // adjust armor art if num below hero art range
-static void __declspec(naked) AdjustHeroArmorArt() {
-	__asm {
-		pop  ebx;                     // get ret addr
-		mov  dword ptr ss:[esp], ebx; // reinsert ret addr in old (push 0)
-		xor  ebx, ebx;
-		push 0;
-		call art_id_;                 // call load frm func
-		mov  dx, ax;
-		and  dh, 0x0F;                // mask out current weapon flag
-		cmp  edx, critterListSize;    // check if critter art in PC range
-		jg   endFunc;
-		add  eax, critterListSize;    // shift critter art index up into hero range
-endFunc:
-		//mov dword ptr ds:[FO_VAR_i_fid], eax;
-		retn;
+void __stdcall AdjustHeroArmorArt(DWORD fid) {
+	if ((fid & 0xF000000) == (OBJ_TYPE_CRITTER << 24) && !PartyControl_IsNpcControlled()) {
+		DWORD fidBase = fid & 0xFFF;
+		if (fidBase <= critterListSize) {
+			*ptr_i_fid += critterListSize;
+		}
 	}
 }
 
@@ -367,76 +359,45 @@ static void DrawPC() {
 }
 
 // scan inventory items for armor and weapons currently being worn or wielded and setup matching FrmID for PC
-void __stdcall RefreshPCArt() {
-	__asm {
-		call proto_dude_update_gender_;         // refresh PC base model art
+void UpdateHeroArt() {
+	TGameObj* iD = *ptr_inven_dude;
+	TGameObj* iR = *ptr_i_rhand;
+	TGameObj* iL = *ptr_i_lhand;
+	TGameObj* iW = *ptr_i_worn;
 
-		push dword ptr ds:[FO_VAR_inven_dude];
-		push dword ptr ds:[FO_VAR_i_rhand]; // item2
-		push dword ptr ds:[FO_VAR_i_lhand]; // item1
-		push dword ptr ds:[FO_VAR_i_worn];  // armor
+	*ptr_i_rhand = 0;
+	*ptr_i_lhand = 0;
+	*ptr_i_worn = 0;
 
-		mov  eax, dword ptr ds:[FO_VAR_obj_dude];     // PC state struct
-		mov  dword ptr ds:[FO_VAR_inven_dude], eax;   // inventory temp pointer to PC state struct
-		mov  eax, dword ptr ds:[FO_VAR_inven_dude];
-		lea  edx, dword ptr ds:[eax + 0x2C];
-		mov  dword ptr ds:[FO_VAR_pud], edx;          // PC inventory
+	*ptr_inven_dude = *ptr_obj_dude;
+	int invenSize = (*ptr_obj_dude)->invenSize;
+	//*ptr_pud = invenSize;
 
-		xor  eax, eax;
-		xor  edx, edx; // itemListOffset
-		xor  ebx, ebx; // itemNum
+	for (int itemNum = 0; itemNum < invenSize; itemNum++) {
+		TGameObj* item = (*ptr_obj_dude)->invenTable[itemNum].object; // PC inventory item list + itemListOffset
 
-		mov  dword ptr ds:[FO_VAR_i_rhand], eax; // item2
-		mov  dword ptr ds:[FO_VAR_i_lhand], eax; // item1
-		mov  dword ptr ds:[FO_VAR_i_worn], eax;  // armor
-		jmp  LoopStart;
-
-CheckNextItem:
-		mov  eax, dword ptr ds:[eax + 0x8]; // PC inventory item list
-		mov  eax, dword ptr ds:[edx + eax]; // PC inventory item list + itemListOffset
-
-		test byte ptr ds:[eax + 0x27], 1; // if item in item1 slot
-		jnz  IsItem1;
-		test byte ptr ds:[eax + 0x27], 2; // if item in item2 slot
-		jnz  IsItem2;
-		test byte ptr ds:[eax + 0x27], 4; // if item in armor slot
-		jnz  IsArmor;
-		jmp  SetNextItem;
-
-IsItem1:
-		mov  dword ptr ds:[FO_VAR_i_lhand], eax; // set item1
-		test byte ptr ds:[eax + 0x27], 2;  // check if same item type also in item2 slot
-		jz   SetNextItem;
-
-IsItem2:
-		mov  dword ptr ds:[FO_VAR_i_rhand], eax; // set item2
-		jmp  SetNextItem;
-
-IsArmor:
-		mov  dword ptr ds:[FO_VAR_i_worn], eax; // set armor
-
-SetNextItem:
-		inc  ebx;    // itemNum++
-		add  edx, 8; // itemListOffset + itemsize
-LoopStart:
-		mov  eax, dword ptr ds:[FO_VAR_pud]; // PC inventory
-		cmp  ebx, dword ptr ds:[eax];  // size of item list
-		jl   CheckNextItem;
-
-		// inventory function - setup pc FrmID and store at address _i_fid
-		call adjust_fid_;
-
-		// copy new FrmID to hero state struct
-		mov  edx, dword ptr ds:[FO_VAR_i_fid];
-		mov  eax, dword ptr ds:[FO_VAR_inven_dude];
-		mov  dword ptr ds:[eax + 0x20], edx;
-		//call obj_change_fid_;
-
-		pop  dword ptr ds:[FO_VAR_i_worn];  // armor
-		pop  dword ptr ds:[FO_VAR_i_lhand]; // item1
-		pop  dword ptr ds:[FO_VAR_i_rhand]; // item2
-		pop  dword ptr ds:[FO_VAR_inven_dude];
+		if (item->flags & ObjectFlag::Right_Hand) {
+			*ptr_i_rhand = item;
+		} else if (item->flags & ObjectFlag::Left_Hand) {
+			*ptr_i_lhand = item;
+		} else if (item->flags & ObjectFlag::Worn) {
+			*ptr_i_worn = item;
+		}
 	}
+
+	// inventory function - setup pc FrmID and store at address _i_fid
+	(*ptr_obj_dude)->artFid = Inventory_adjust_fid(); // adjust_fid_
+
+	*ptr_inven_dude = iD;
+	*ptr_i_rhand = iR;
+	*ptr_i_lhand = iL;
+	*ptr_i_worn = iW;
+}
+
+void __stdcall RefreshPCArt() {
+	fo_proto_dude_update_gender(); // refresh PC base model art
+
+	UpdateHeroArt();
 	DrawPC();
 }
 
@@ -1462,7 +1423,7 @@ static void EnableHeroAppearanceMod() {
 	MakeCall(0x49F9DA, AdjustHeroBaseArt);
 
 	// Adjust hero art index offset when changing armor (adjust_fid_)
-	HookCall(0x4717D1, AdjustHeroArmorArt);
+	/* HookCall(0x4717D1, AdjustHeroArmorArt); - the engine function is replaced by the sfall code */
 
 	// Hijack Save Hero State Structure fuction address 9CD54800
 	// Return hero art index offset back to normal before saving
diff --git a/sfall/HeroAppearance.h b/sfall/HeroAppearance.h
index 018b7f58..bd85c963 100644
--- a/sfall/HeroAppearance.h
+++ b/sfall/HeroAppearance.h
@@ -18,9 +18,13 @@
 
 #pragma once
 
+extern bool appModEnabled;
+
 void HeroAppearance_Init();
 void HeroAppearance_Exit();
 
+void __stdcall AdjustHeroArmorArt(DWORD fid);
+
 void __stdcall HeroSelectWindow(int raceStyleFlag);
 void __stdcall SetHeroStyle(int newStyleVal);
 void __stdcall SetHeroRace(int newRaceVal);
diff --git a/sfall/HookScripts.cpp b/sfall/HookScripts.cpp
index dd9d58a1..cc733199 100644
--- a/sfall/HookScripts.cpp
+++ b/sfall/HookScripts.cpp
@@ -1586,6 +1586,21 @@ long __stdcall CorrectFidForRemovedItem_wHook(TGameObj* critter, TGameObj* item,
 	return result;
 }
 
+// 4.x backport
+void __stdcall AdjustFidHook(DWORD vanillaFid) {
+	BeginHook();
+	argCount = 2;
+
+	args[0] = vanillaFid;
+	args[1] = *ptr_i_fid; // modified FID by sfall code
+	RunHookScript(HOOK_ADJUSTFID);
+
+	if (cRet > 0) {
+		*ptr_i_fid = rets[0];
+	}
+	EndHook();
+}
+
 // 4.x backport
 static unsigned long previousGameMode = 0;
 
@@ -1635,7 +1650,7 @@ void __stdcall SetHSReturn(DWORD value) {
 }
 
 void __stdcall RegisterHook(TProgram* script, int id, int procNum, bool specReg) {
-	if (id >= numHooks || (id > HOOK_INVENWIELD && id < HOOK_GAMEMODECHANGE)) return;
+	if (id >= numHooks || (id > HOOK_ADJUSTFID && id < HOOK_GAMEMODECHANGE)) return;
 	for (std::vector<sHookScript>::iterator it = hooks[id].begin(); it != hooks[id].end(); ++it) {
 		if (it->prog.ptr == script) {
 			if (procNum == 0) hooks[id].erase(it); // unregister
@@ -1873,6 +1888,7 @@ static void HookScriptInit() {
 	HookCall(0x45C4F6, op_move_obj_inven_to_obj_hook);
 	MakeCall(0x4778AF, item_drop_all_hack, 3);
 
+	LoadHookScript("hs_adjustfid", HOOK_ADJUSTFID);
 	LoadHookScript("hs_gamemodechange", HOOK_GAMEMODECHANGE);
 
 	fo_db_free_file_list(&filenames, 0);
diff --git a/sfall/HookScripts.h b/sfall/HookScripts.h
index 3057f3c4..eac0f3e5 100644
--- a/sfall/HookScripts.h
+++ b/sfall/HookScripts.h
@@ -46,6 +46,7 @@ enum HookType
 	HOOK_WITHINPERCEPTION = 23,
 	HOOK_INVENTORYMOVE    = 24,
 	HOOK_INVENWIELD       = 25,
+	HOOK_ADJUSTFID        = 26, // 4.x backport
 	HOOK_GAMEMODECHANGE   = 31, // 4.x backport
 	HOOK_COUNT
 };
@@ -65,17 +66,20 @@ void HookScriptClear();
 
 extern DWORD initingHookScripts;
 
-int __fastcall AmmoCostHook_Script(DWORD hookType, TGameObj* weapon, DWORD &rounds);
 void __stdcall RunHookScriptsAtProc(DWORD procId);
 
 void __stdcall GameModeChangeHook(DWORD exit);
 void __stdcall KeyPressHook(DWORD* dxKey, bool pressed, DWORD vKey);
 void __stdcall MouseClickHook(DWORD button, bool pressed);
 
+int __fastcall AmmoCostHook_Script(DWORD hookType, TGameObj* weapon, DWORD &rounds);
+
 long __stdcall CorrectFidForRemovedItem_wHook(TGameObj* critter, TGameObj* item, long flags);
 void InvenUnwield_HookDrop();
 void InvenUnwield_HookMove();
 
+void __stdcall AdjustFidHook(DWORD vanillaFid);
+
 // Implementation of item_w_mp_cost_ engine function with the hook
 long __fastcall sf_item_w_mp_cost(TGameObj* source, long hitMode, long isCalled);
 
diff --git a/sfall/Inventory.cpp b/sfall/Inventory.cpp
index 3967b37c..f6daf3b2 100644
--- a/sfall/Inventory.cpp
+++ b/sfall/Inventory.cpp
@@ -20,8 +20,11 @@
 
 #include "main.h"
 #include "FalloutEngine.h"
+#include "HeroAppearance.h"
+#include "HookScripts.h"
 #include "InputFuncs.h"
 #include "LoadGameHook.h"
+#include "PartyControl.h"
 
 #include "Inventory.h"
 
@@ -58,9 +61,9 @@ void InventoryKeyPressedHook(DWORD dxKey, bool pressed) {
 	}
 }
 
-/////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
 
-DWORD __stdcall sf_item_total_size(TGameObj* critter) {
+DWORD __stdcall Inventory_item_total_size(TGameObj* critter) {
 	int totalSize = fo_item_c_curr_size(critter);
 
 	if (critter->TypeFid() == OBJ_TYPE_CRITTER) {
@@ -82,6 +85,70 @@ DWORD __stdcall sf_item_total_size(TGameObj* critter) {
 	return totalSize;
 }
 
+// Reimplementation of adjust_fid engine function
+// Differences from vanilla:
+// - doesn't use art_vault_guy_num as default art, uses current critter FID instead
+// - calls AdjustFidHook that allows to hook into FID calculation
+DWORD __stdcall Inventory_adjust_fid() {
+	DWORD fid;
+	if ((*ptr_inven_dude)->TypeFid() == OBJ_TYPE_CRITTER) {
+		DWORD indexNum;
+		DWORD weaponAnimCode = 0;
+		if (PartyControl_IsNpcControlled()) {
+			// if NPC is under control, use current FID of critter
+			indexNum = (*ptr_inven_dude)->artFid & 0xFFF;
+		} else {
+			// vanilla logic:
+			indexNum = *ptr_art_vault_guy_num;
+			auto critterPro = GetProto(*ptr_inven_pid);
+			if (critterPro != nullptr) {
+				indexNum = critterPro->fid & 0xFFF;
+			}
+			if (*ptr_i_worn != nullptr) {
+				auto armorPro = GetProto((*ptr_i_worn)->protoId);
+				DWORD armorFid = fo_stat_level(*ptr_inven_dude, STAT_gender) == GENDER_FEMALE
+					? armorPro->item.armor.femaleFID
+					: armorPro->item.armor.maleFID;
+
+				if (armorFid != -1) {
+					indexNum = armorFid;
+				}
+			}
+		}
+		auto itemInHand = fo_intface_is_item_right_hand()
+			? *ptr_i_rhand
+			: *ptr_i_lhand;
+
+		if (itemInHand != nullptr) {
+			auto itemPro = GetProto(itemInHand->protoId);
+			if (itemPro->item.type == item_type_weapon) {
+				weaponAnimCode = itemPro->item.weapon.animationCode;
+			}
+		}
+		fid = fo_art_id(OBJ_TYPE_CRITTER, indexNum, 0, weaponAnimCode, 0);
+	} else {
+		fid = (*ptr_inven_dude)->artFid;
+	}
+	*ptr_i_fid = fid;
+	// OnAdjustFid
+	if (appModEnabled) AdjustHeroArmorArt(fid);
+	AdjustFidHook(fid); // should be called last
+	return *ptr_i_fid;
+}
+
+static void __declspec(naked) adjust_fid_hack() {
+	__asm {
+		push ecx;
+		push edx;
+		call Inventory_adjust_fid; // return fid
+		pop  edx;
+		pop  ecx;
+		retn;
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 static int __stdcall CritterGetMaxSize(TGameObj* critter) {
 	if (critter == *ptr_obj_dude) return invSizeMaxLimit;
 
@@ -108,7 +175,7 @@ static __declspec(naked) void critterIsOverloaded_hack() {
 		jz   skip;
 		push ebx;
 		mov  ebx, eax;           // ebx = MaxSize
-		call sf_item_total_size;
+		call Inventory_item_total_size;
 		cmp  eax, ebx;
 		setg al;                 // if CurrSize > MaxSize
 		and  eax, 0xFF;
@@ -122,8 +189,8 @@ end:
 static int __fastcall CanAddedItems(TGameObj* critter, TGameObj* item, int count) {
 	int sizeMax = CritterGetMaxSize(critter);
 	if (sizeMax > 0) {
-		int itemsSize = fo_item_size(item) * count;
-		if (itemsSize + (int)sf_item_total_size(critter) > sizeMax) return -6; // TODO: Switch this to a lower number, and add custom error messages.
+		int totalSize = Inventory_item_total_size(critter) + (fo_item_size(item) * count);
+		if (totalSize > sizeMax) return -6; // TODO: Switch this to a lower number, and add custom error messages.
 	}
 	return 0;
 }
@@ -168,10 +235,10 @@ static int __fastcall BarterAttemptTransaction(TGameObj* critter, TGameObj* tabl
 	int size = CritterGetMaxSize(critter);
 	if (size == 0) return 1;
 
-	int sizeTable = sf_item_total_size(table);
+	int sizeTable = Inventory_item_total_size(table);
 	if (sizeTable == 0) return 1;
 
-	size -= sf_item_total_size(critter);
+	size -= Inventory_item_total_size(critter);
 	return (sizeTable <= size) ? 1 : 0;
 }
 
@@ -246,7 +313,7 @@ static void __cdecl DisplaySizeStats(TGameObj* critter, const char* &message, DW
 	}
 
 	sizeMax = limitMax;
-	size = sf_item_total_size(critter);
+	size = Inventory_item_total_size(critter);
 
 	const char* msg = MsgSearch(ptr_inventry_message_file, 35);
 	message = (msg != nullptr) ? msg : "";
@@ -312,14 +379,15 @@ static void __declspec(naked) gdControlUpdateInfo_hack() {
 		call CritterGetMaxSize;
 		push eax;               // sizeMax
 		push ebx;
-		call sf_item_total_size;
+		call Inventory_item_total_size;
 		push eax;               // size
 		mov  eax, ebx;
 		mov  edx, STAT_carry_amt;
 		jmp  ControlUpdateInfoRet;
 	}
 }
-/////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////////////
 
 static char superStimMsg[128];
 static int __fastcall SuperStimFix(TGameObj* item, TGameObj* target) {
@@ -634,6 +702,9 @@ void InventoryReset() {
 }
 
 void Inventory_Init() {
+	// Replace adjust_fid_ function
+	MakeJump(adjust_fid_, adjust_fid_hack); // 0x4716E8
+
 	long widthWeight = 135;
 
 	sizeLimitMode = GetConfigInt("Misc", "CritterInvSizeLimitMode", 0);
diff --git a/sfall/Inventory.h b/sfall/Inventory.h
index b227c953..82844d89 100644
--- a/sfall/Inventory.h
+++ b/sfall/Inventory.h
@@ -24,4 +24,14 @@ void InventoryKeyPressedHook(DWORD dxKey, bool pressed);
 
 long __stdcall GetInvenApCost();
 void __fastcall SetInvenApCost(int cost);
-DWORD __stdcall sf_item_total_size(TGameObj* critter);
+
+// This function returns the size of the occupied inventory space for the object or critter
+// - difference from the item_c_curr_size_ function: includes the size of equipped items for the critter
+// - does not return the size of nested items
+DWORD __stdcall Inventory_item_total_size(TGameObj* critter);
+
+// Reimplementation of adjust_fid engine function
+// Differences from vanilla:
+// - doesn't use art_vault_guy_num as default art, uses current critter FID instead
+// - calls AdjustFidHook that allows to hook into FID calculation
+DWORD __stdcall Inventory_adjust_fid();
diff --git a/sfall/ScriptOps/ObjectsOps.hpp b/sfall/ScriptOps/ObjectsOps.hpp
index 3ec5560e..69adb07d 100644
--- a/sfall/ScriptOps/ObjectsOps.hpp
+++ b/sfall/ScriptOps/ObjectsOps.hpp
@@ -524,7 +524,7 @@ static void mf_set_unjam_locks_time() {
 static void mf_get_current_inven_size() {
 	TGameObj* obj = opHandler.arg(0).asObject();
 	if (obj) {
-		opHandler.setReturn(sf_item_total_size(obj));
+		opHandler.setReturn(Inventory_item_total_size(obj));
 	} else {
 		OpcodeInvalidArgs("get_current_inven_size");
 		opHandler.setReturn(0);